Electric safety-switch



A. W. STANHOPE.

ELECTRIC SAFETY SWITCH.

APPLICATION FILED JAN. 11, I920.

1,355,179. Patented Oct. 12,1920.

IN V EN TOR,

wM//M 44 ATTORNEY.

' UNITED STATES ALFRED w. s'mnnorn, or DAYTON, OHIO.

ELECTRIC sArnrY-swrrcnj i T 0 all whom it may conccm 1 Be it known that I, ALFRED XV. STANHO PE,

a 'citizen'of the United States, residing at Dayton, in the county of Montgomery and State of Ohio, have invented certain new.

and useful Improvements in Electric Safety- Switches, of which the following is a specl- V fication.

The principal object of myinventio'n is to provide means for automatically holding open, after an emergency plunger has been.

depressed, an electric safety switch that is commonly employed to shut off the current in machines after an accident has occurred. In switches of the type disclosed in the drawing, the plunger, in the absence of an automatic stop, must be held downby thehand to keep the circuit open long enough to V bring to rest the machine in which an open atives limb may have been caught. i

It has been found by experience that when an accident occurs, and the j'plunger depressed, pressure is removed from it too quickly to open the circuit long enough to stop the machine. This is "often due to the fact that an operative who is caught in a machine, is unable to hold the plunger down after it has been depressed; Therefore, my-

improved means have been devised for auto- 'matically holding the switch open after the plunger thereof has'been depressed.

The preferred form of embodiment of my invention is illustrated in the accompanying drawing, of which Figure 1 is 'a side eleva- 'tional view of a safety switch showing the position of my improved automatic stop therein before the plunger has been depressed. Fig. 2 1s a side elevational view of automatic stop. Fig. 3 is a detail sectional view showing the position of the rotatable contact with reference to the fixed ones when the circuit is held open by the "auto- .matic stop. -Fig. dis 'a detail sectional view a Specification of Letters Pa Patented Oct.f12, 1920. Application filed January 17, 1920. Serial Ito/352 942.

numeral 1 designates a switch box that is preferablyrectangular in cross. section. Integral with the nner upper portions of the end walls of said box, are two oppositely disposed lugs 2, 2 that receive a. transverse contact] tongue 8 in an inclined position is adapted to engage the curved spring-ends of a pair of contact members 9, '9 fixedly, secured at their inner endsto an insulating block 10 fixedly'secured withinthe casing 1..

PATENT o HcEf a WV hen the contact.-members'9,"9 are engaged at their forwardends by the tongue 8,'an electric circuit is completed through it and the contact members 9-,= 9. inthe usual way.

' For the purpose of opening j'th-is circuit,

the insulating block 7 is turned to a position about the spindle 3 to withdraw the tongue 8 [from engagement with the contacts 9, 9 as shownin Figs. 2 and 3, by the following means. Pivoted to the outer end of the arm '6 is a roller 11 which is received between sleeves 12 and 18 fixedly secured to a-plun- "ger 14. The sleeve 12 projects upw-ardly through a boss 15 and the top of the casing 1 tegral, said sleeve terminating in -ahead 16. The lower end ofthe "plunger 14 projects through a coil spring 17 into a boss 18 integral with the bottom. ofthe "switch-box 1. The lower end of said spring 17; rests in a cupped member 19 supported by the bofsslS, while the top of-said.springpresses upwardly against a,-'cupped-;piece 20 that encircles the plunger and bears against the sleeve 13 on the latter.

Then the plunger 14 is depressed against the tension of thespring-17. the. sleeves 12 "and 13 will force-downwardly the roller 11 between them/to cause the' arm'S-Which carries it to turn the insulating :b'lock about the contact tongue 8 out of engagement with the contacts 9, 9 as shown in Figs. 2 and 3, for the purpose of opening the circuit that is established through said contacts and a ma with whose under surface said boss is in;

spindle '3 a sufficient distance to bring the i 7 proved automatic stop now to be described,

chine not shown. it were not for my imthe spring 17 would force the plunger lt upwardly to its circuit .closinggposition when the pressure thereon is removed.

Referring to F :1; and 2, there is secured within a transverse hole in the right end wall of the switch box'l, a tubular insulatingmember 21 that terminates outside}, the wall of'the switch box in a'dislr-s'haped flange portion 22which is secured to said wall by) screws "23 Projecting loosely throughthe tubular member 21 is a plunger 2Q encircling which, behind a collar 25, is a (301i spring26 adapted to exert ts pressure 1 against the collar 25 to'force tliegfront end of the plunger across the path of upward movement of theouter endot thearm 6 aftrth plunger 14: has been 7 depressed,"

The plunger" 14 is thereby. gheldilin its deypressed'positi'on' automatically to hold open outer endofthe plunger. When the plunger 24is'drawn outwardly, thecoil spring' 26 surrounding itbetween the collar- 25 and the "interior portion of the tubular member 7' I 21, is-compressed'by the outer end of the I arm6 whose side face is now engaged by'the .frontend of-theplunger 24. Their when the plungerl tis again depressedto open the 'switchcircuit, the outer end of the arm 6 will be Qcarried below the front end of the plunger 24, whereupon the spring] 17 will force saidplunger end across the path of upward movementfof the arm 6"automatically to hold the circuit open until the 'plunger' 24 is again drawn inwardly. An

Ina machine is thus assured that whenthe' plunger 14:- is depressed to open the circuit forthe purpose of stopping the machine, the circuit' will' beheld open by my improved g plunger hasbeen removed. H Having described my invention, I claim :1

operativewho may be accidentally-caught automatic stop after pressure upon the 1. Inan electric safety switch, the 'coinbination with a pair of spaced fixed contacts, of a rotatable'contact adapted'to be turned into" andout ofengagementwith the fixed v 'contacts'to close-and open the switch circuit,

a plunger, an arm for turning said rotatable contact, means "on said plunger adapted, when the plunger is depressed, to movesaid arm downwardly to turn the rotatable contact out fiof engagement with the fixed contacts, aspring for returning said plunger,

' and through it the'lrotatable contact, to its circuit-closing position,-a stop member, and

" means adapted to project said stop'member sitionl 7 i In a' device loft-he type described,the

automatically across the path of upward movement of said arm, to preventthe return of the rotatable contact to its circuit-closing position until said stop member is with-c drawn from its position above said "52. In an electric safety switch, the icombi-l nation with a pair of spaced fixed contacts,

iofa-rotatablecontact adapted to be turned when the plunger is depressed, to move said arm downwardly to turn therotatable con- .tact out of en a ement with the fixed contacts, a spring ior'returning said plunger,

and through it the rotatable ccntacflto' its circuit closing position, a tubular member, plunger"flmovable through said tubular lmemberacross the path of upward move V ment of said arm when' thefirst plunger is' p the circuit through the switch until the plunger 24iiswithdrawn from engagement" :with-thearm' 6 by a: knurled disk 27on the depressechend a springencircling the second plunger for forcingits front end automatically above said arm to prevent thereis withdrawn from saidarm engaging po combination with a-switchbox, ofa pair of contacts fixedly secured thereiin-a rotatable contact adapted to be turned-into andout of engagement with'the fixed contacts to close-and open the switch circuit, aplu-nger,

an arm for turning said rotatable contact, means on said plunger adapted, when the plunger is depressed, to' move said arm downwardly to' turn the rotatable contact out of engagement with the fixed contacts, a spring for returning said plunger, and

through it'the rotatable contact, toits cir-' cuit 'closing position, a tubular 'member 7 transversely projected through a holein said box opposite said arm, a flange on the outer end of said tubular member, secured to said box, a plunger 'movablethroughisaid tubular member, a collar on the frontend of said plunger, and a coil spring encirclingsaid 110 iinterior P01131011 of the tubular member, to

second plunger between said collar and the force the front end of said plunger above said arm when the first plunger is-depressed, to prevent :thereturn. of the rotatable 'con tact to its circuit closing position until said secondplunger is withdrawn from its posi tion abovesaid arm; I f i i In testimony whereof Ihave hereunto set this 14th day of January, 1920.

my hand I cLFRED STANHQPE.

. Witness 1 HOWARD S. SMITH. 

